1. Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly to a transreflective type LCD and a method of manufacturing the same for increasing an available efficiency of a light and a color reproducibility of an image.
2. Description of the Related Art
In the so-called information society of these days, electronic display devices are important as information transmission media and various electronic display devices are widely applied to industrial apparatus or home appliances. Recently, demand has increased for a new electronic display devices such as an LCD having characteristics such as thin thickness, light weight, low driving voltage and low power consumption. Manufacturing of an LCD has been improved due to advances in semiconductor technology.
The LCD is classified as a transmissive type LCD that displays an image using a first light provided from an external, a reflective type LCD that displays an image using a second light generated by a light generating means installed therein, and a transreflective type LCD that displays the image using either the first light or the second light. The transreflective type LCD displays an image using the first light in a case where an amount of the first light is enough to display the image and displays the image using the second light generated by consuming electricity charged into itself where the amount of the first light is not enough to display the image. Thus, the transreflective type LCD reflects the first light and transmits the second light.
FIG. 1 is a cross-sectional view showing an internal structure of an LCD panel of a conventional transreflective type LCD.
Referring to FIG. 1, the transreflective type LCD 100 includes a color filter substrate 110, a liquid crystal 120 and a TFT (thin film transistor) substrate 130. The TFT substrate 130 includes a transparent substrate 131, a TFT 132, an organic insulating layer 133, a transparent electrode 134, a reflective electrode 135 and an alignment layer 136 having an alignment groove 136a. 
The TFT 132 is disposed on the transparent substrate 131 in a matrix shape. The TFT 132 outputs a data signal from an external in response to a timing signal. The organic insulating layer 133 is disposed over the transparent substrate 131 to cover the TFT 132. The organic insulating layer 133 has an uneven surface 133a and a contact hole 133b to expose an output terminal of the TFT 132. The transparent electrode 134 is formed by forming an ITO (Indium Thin Oxide) thin film layer over the organic insulating layer 133 and patterning the ITO thin film layer to be connected with the output terminal of the TFT 132. The reflective electrode 135 is disposed on the transparent electrode 134. The reflective electrode 135 has an opening 135a and a portion of the transparent electrode 134 is exposed through the opening 135a. The alignment layer 136 is disposed over the transparent substrate 131 to cover the reflective electrode 135 and the alignment groove 136a is formed on the alignment layer 136.
The color filter substrate 110 includes a transparent substrate 111, a black matrix 112, a color filter 113, a common electrode 114 and an alignment layer 115. The black matrix 112 disposed on the transparent substrate 111 has a lattice shape and faces an insulating space 135c disposed adjacent to the reflective electrode 135 of the TFT substrate 130. The transparent substrate 111 includes the color filter 113 in a matrix shape corresponding to the reflective electrode 135. The color filter 113 includes a red color filter for emitting a monochromatic light having a red wavelength, a green color filter for emitting a monochromatic light having a green wavelength and a blue color filter for emitting a monochromatic light having a blue wavelength by filtering the light.
The common electrode 114 is disposed over the transparent substrate 111 to cover an upper surface of the color filter 113. The alignment layer 115 is disposed on the transparent substrate 111 to cover the common electrode 114 and the alignment groove 115a is formed on the alignment layer 115. The color filter substrate 110 is combined to the TFT substrate 130. The liquid crystal 120 is injected between the color filter substrate 110 and the TFT substrate 130.
Where the amount of the light is not enough to display the image, the transreflective type LCD supplies a light having a first direction from the TFT substrate 130 toward the color filter substrate 110 by consuming an electric energy charged therein. In this transmissive mode, the light having the first direction is supplied to a user 140 through the opening 135a, the liquid crystal 120, the color filter 113 and the transparent substrate 111. Where an amount of the first light is enough to display the image, the transreflective type LCD receives a light having a second direction from an external and a lamp (not shown) is turned off. In this reflective mode, the transreflective type LCD receives the light having the second direction through the transparent substrate 111, the color filter 113, the liquid crystal 120 and the reflective electrode 135 and the light incident into the transreflective type LCD is supplied to the user 140 through the liquid crystal 120, the color filter 113 and the transparent substrate 111.
The light (hereinafter, referred to as an artificial light) from the color filter 113 in the transmissive mode has a different color tone and an impression of the color from those of the light (hereinafter, referred to as a natural light) from the color filter 113 in the reflective mode. This is because a light path inside the LCD is different according to the light source. The natural light passes through the color filter 113 twice in the reflective mode and the artificial light passes through the color filter 113 only once in the transmissive mode. That is, the length through which the natural light passes is about twice greater than the length through which the artificial light passes. The differences according to the display mode between the transmissive mode and the reflective mode result in a deterioration of the image.
Further, it is difficult to maintain a shape of the uneven surface 133a of the organic layer 133 due to thin film layers disposed under the organic layer 133. The uniformity of the light is not desirably maintained in the transreflective LCD, so that display and visual properties are deteriorated.